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Journal Articles

On the adsorption and reactivity of element 114, flerovium

Yakushev, A.*; Lens, L.*; D$"u$llmann, Ch. E.*; Khuyagbaatar, J.*; J$"a$ger, E.*; Krier, J.*; Runke, J.*; Albers, H. M.*; Asai, Masato; Block, M.*; et al.

Frontiers in Chemistry (Internet), 10, p.976635_1 - 976635_11, 2022/08

 Times Cited Count:17 Percentile:78.72(Chemistry, Multidisciplinary)

Flerovium (Fl, element 114) is the heaviest element chemically studied so far. The first chemical experiment on Fl suggested that Fl is a noble-gas-like element, while the second studies suggested that Fl has a volatile-metal-like character. To obtain more reliable conclusion, we performed further experimental studies on Fl adsorption behavior on Si oxide and gold surfaces. The present results suggest that Fl is highly volatile and less reactive than the volatile metal, Hg, but has higher reactivity than the noble gas, Rn.

Journal Articles

Environmental effects on layer-dependent dynamics of Dirac fermions in quasicrystalline bilayer graphene

Zhao, Y.*; Suzuki, T.*; Iimori, T.*; Kim, H.-W.*; Ahn, J. R.*; Horio, Masafumi*; Sato, Yusuke*; Fukaya, Yuki; Kanai, T.*; Okazaki, K.*; et al.

Physical Review B, 105(11), p.115304_1 - 115304_8, 2022/03

 Times Cited Count:1 Percentile:8.90(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Production of $$^{266}$$Bh in the $$^{248}$$Cm($$^{23}$$Na,5$$n$$)$$^{266}$$Bh reaction and its decay properties

Haba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.

Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08

 Times Cited Count:6 Percentile:52.67(Physics, Nuclear)

Journal Articles

Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions

Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.

Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02

 Times Cited Count:28 Percentile:82.18(Physics, Multidisciplinary)

Journal Articles

Extraction behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from HF/HNO $$_{3}$$ acidic solutions

Yokoyama, Akihiko*; Kitayama, Yuta*; Fukuda, Yoshiki*; Kikunaga, Hidetoshi*; Murakami, Masashi*; Komori, Yukiko*; Yano, Shinya*; Haba, Hiromitsu*; Tsukada, Kazuaki; Toyoshima, Atsushi*

Radiochimica Acta, 107(1), p.27 - 32, 2019/01

 Times Cited Count:1 Percentile:9.36(Chemistry, Inorganic & Nuclear)

Journal Articles

Online chemical adsorption studies of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

AA2018-0417.pdf:0.99MB

 Times Cited Count:11 Percentile:66.48(Chemistry, Inorganic & Nuclear)

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO$$_{2}$$ or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO$$_{2}$$ surface at room temperature. On the other hand, the Hg did not adsorb on the SiO$$_{2}$$ surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Journal Articles

Extraction behavior of Mo and W from H$$_{2}$$SO$$_{4}$$ and HF/HCl solutions into toluene with Aliquat336; Sulfate and fluoride complex formation of Mo and W towards chemical studies of seaborgium (Sg)

Toyoshima, Atsushi; Mitsukai, Akina; Tsukada, Kazuaki; Oe, Kazuhiro*; Haba, Hiromitsu*; Komori, Yukiko*; Murakami, Masashi; Kaneya, Yusuke*; Sato, Daisuke*; Asai, Masato; et al.

Journal of Radioanalytical and Nuclear Chemistry, 317(1), p.421 - 430, 2018/07

 Times Cited Count:3 Percentile:26.77(Chemistry, Analytical)

We have studied extraction behavior of group-6 elements Mo and W to search for suitable conditions for an on-line extraction experiment of their heavier homolog, seaborgium (Sg). Batch-wise extraction of carrier-free radiotracers $$^{93m}$$Mo and $$^{177,179,181}$$W were carried out from 0.10 - 8.6 M H$$_{2}$$SO$$_{4}$$ and 1.0$$times$$10$$^{-4}$$ - 5.0 M HF/1.0 M HCl into toluene with a quaternary ammonium compound, Aliquat336. Anionic sulfate complexes of Mo and W with charge - 2 were extracted with Aliquat336 from H$$_{2}$$SO$$_{4}$$ solutions with concentrations of [H$$_{2}$$SO$$_{4}$$] $$>$$ 2 M. In HF/1.0 M HCl, oxyfluoro complexes of Mo and W with charge - 1 were interpreted to be formed and extracted with Aliquat336. From these results, favorable conditions for the extraction of Sg are discussed.

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:21 Percentile:75.07(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Study of the reaction $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ at RIKEN-GARIS

Kaji, Daiya*; Morita, Kosuke*; Morimoto, Koji*; Haba, Hiromitsu*; Asai, Masato; Fujita, Kunihiro*; Gan, Z.*; Geissel, H.*; Hasebe, Hiroo*; Hofmann, S.*; et al.

Journal of the Physical Society of Japan, 86(3), p.034201_1 - 034201_7, 2017/03

 Times Cited Count:31 Percentile:82.79(Physics, Multidisciplinary)

The fusion reaction of $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ was studied using the gas-filled recoil-ion separator GARIS at RIKEN. A total of seven $$alpha$$ and spontaneous-fission decay chains were observed, which would originate from the reaction products of the element 116, $$^{292}$$Lv and $$^{293}$$Lv. Decay properties observed in the chains are in good agreement with the previously published ones. However, one of the chains showed a discrepancy, indicating the new spontaneous-fission branch in $$^{285}$$Cn or the production of the new isotope $$^{294}$$Lv.

Journal Articles

Complex chemistry with complex compounds

Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; D$"u$llmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.

EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12

 Times Cited Count:3 Percentile:72.00(Chemistry, Inorganic & Nuclear)

In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO)$$_{6}$$. Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO)$$_{6}$$, W(CO)$$_{6}$$, and Sg(CO)$$_{6}$$.

Journal Articles

Production of $$^{88}$$Nb and $$^{170}$$Ta for chemical studies of element 105, Db, using the GARIS gas-jet system

Huang, M.*; Haba, Hiromitsu*; Murakami, Masashi*; Asai, Masato; Kaji, Daiya*; Kanaya, Jumpei*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Kikutani, Yuki*; Komori, Yukiko*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 304(2), p.845 - 849, 2015/05

 Times Cited Count:3 Percentile:24.31(Chemistry, Analytical)

A technique to utilize radioisotopes of Nb and Ta was developed for chemical studies of element 105, Db, by coupling a gas-jet transport system to the RIKEN gas-filled recoil ion separator (GARIS). The short-lived $$^{88}$$Nb and $$^{170}$$Ta were produced with nuclear reactions using a $$^{19}$$F beam whose energy was the same as that to produce $$^{262}$$Db. Then, they were separated with GARIS and extracted to a chemistry laboratory with the gas-jet transport system. By changing only magnetic field of GARIS and inserting an energy degrader and a shutter for recoil ions, we could deliver the $$^{88}$$Nb and $$^{170}$$Ta to a chemistry device for $$^{262}$$Db without changing other experimental conditions.

Journal Articles

Monitoring of positron using high-energy gamma camera for proton therapy

Yamamoto, Seiichi*; Toshito, Toshiyuki*; Komori, Masataka*; Morishita, Yuki*; Okumura, Satoshi*; Yamaguchi, Mitsutaka; Saito, Yuichi; Kawachi, Naoki; Fujimaki, Shu

Annals of Nuclear Medicine, 29(3), p.268 - 275, 2015/04

 Times Cited Count:22 Percentile:66.95(Radiology, Nuclear Medicine & Medical Imaging)

Journal Articles

Solid-liquid extraction of Mo and W by Aliquat 336 from HCl solutions toward extraction chromatography experiments of Sg

Komori, Yukiko*; Yokokita, Takuya*; Kasamatsu, Yoshitaka*; Haba, Hiromitsu*; Toyoshima, Atsushi; Toyomura, Keigo*; Nakamura, Kohei*; Kanaya, Jumpei*; Huang, M.*; Kudo, Yuki*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1385 - 1388, 2015/02

 Times Cited Count:2 Percentile:16.44(Chemistry, Analytical)

We studied solid-liquid extraction behavior of carrier-free Mo and W radiotracers onto an Aliquat 336-loaded resin from HCl solutions toward extraction chromatography experiments of element 106, seaborgium(Sg). Distribution coefficients ($${it K}$$$$_{d}$$) of Mo and W on the resin were determined as a function of HCl concentration by a batch method. On-line extraction chromatography of Mo and W was also carried out in 2-8 M HCl solutions with an automated rapid chemistry apparatus. The order of extraction probability from 2 to 8 M HCl was Mo$$>$$W, which reflected the order of the $${it K}$$$$_{d}$$ values in the batch experiment.

Journal Articles

Development of a new continuous dissolution apparatus with a hydrophobic membrane for superheavy element chemistry

Oe, Kazuhiro*; Attallah, M. F.*; Asai, Masato; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Huang, M.*; Kanaya, Jumpei*; Kaneya, Yusuke*; Kasamatsu, Yoshitaka*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1317 - 1320, 2015/02

 Times Cited Count:10 Percentile:61.82(Chemistry, Analytical)

A new technique for continuous dissolution of nuclear reaction products transported by a gas-jet system was developed for superheavy element (SHE) chemistry. In this technique, a hydrophobic membrane is utilized to separate an aqueous phase from the gas phase. With this technique, the dissolution efficiencies of short-lived radionuclides of $$^{91m,93m}$$Mo and $$^{176}$$W were measured. Yields of more than 80% were observed for short-lived radionuclides at aqueous-phase flow rates of 0.1-0.4 mL/s. The gas flow-rate had no influence on the dissolution efficiency within the studied flow range of 1.0-2.0 L/min. These results show that this technique is applicable for on-line chemical studies of SHEs in the liquid phase.

Journal Articles

Production of $$^{262}$$Db in the $$^{248}$$Cm($$^{19}$$F,5$$n$$)$$^{262}$$Db reaction and decay properties of $$^{262}$$Db and $$^{258}$$Lr

Haba, Hiromitsu*; Huang, M.*; Kaji, Daiya*; Kanaya, Jumpei*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Murakami, Masashi*; Ozeki, Kazutaka*; Sakai, Ryutaro*; et al.

Physical Review C, 89(2), p.024618_1 - 024618_11, 2014/02

 Times Cited Count:26 Percentile:81.76(Physics, Nuclear)

Journal Articles

Current status of JMTR

Ishihara, Masahiro; Kimura, Nobuaki; Takemoto, Noriyuki; Ooka, Makoto; Kaminaga, Masanori; Kusunoki, Tsuyoshi; Komori, Yoshihiro; Suzuki, Masahide

Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 7 Pages, 2012/10

The JMTR has been utilized for fuel/material irradiation examinations of LWRs, HTGR, fusion reactor as well as for RI productions. The refurbishment of the JMTR was started from the beginning of JFY 2007, and finished in March 2011 as planned schedule. Unfortunately, at the end of the JFY 2010 on March 11, the Great-Eastern-Japan-Earthquake occurred, and functional tests before the JMTR restart were delayed by the earthquake. Moreover, a detail inspection found some damages such as small cracks in the concrete structure, ground sinking around the reactor building. Consequently, the restart will delay from June 2011. Now, the safety evaluation of the facility after the earthquake disaster is being carried out aiming at the restart of the JMTR. The renewed JMTR will be started from JFY 2012 and operated for a period of about 20 years until around JFY 2030. The usability improvement of the JMTR is also discussed with users as the preparations for re-operation.

Journal Articles

Sulfate complexation of element 104, Rf, in H$$_{2}$$SO$$_{4}$$/HNO$$_{3}$$ mixed solution

Li, Z.*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Nagame, Yuichiro; Sch$"a$del, M.; Pershina, V.*; et al.

Radiochimica Acta, 100(3), p.157 - 164, 2012/03

 Times Cited Count:14 Percentile:69.68(Chemistry, Inorganic & Nuclear)

Journal Articles

Production of $$^{265}$$Sg in the $$^{248}$$Cm($$^{22}$$Ne,5$$n$$)$$^{265}$$Sg reaction and decay properties of two isomeric states in $$^{265}$$Sg

Haba, Hiromitsu*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sakai, Ryutaro*; Sumita, Takayuki*; Yoneda, Akira*; Kasamatsu, Yoshitaka*; et al.

Physical Review C, 85(2), p.024611_1 - 024611_11, 2012/02

 Times Cited Count:55 Percentile:91.21(Physics, Nuclear)

Two isomeric states in $$^{265}$$Sg, i.e, $$^{265}$$Sg$$^{a}$$ and $$^{265}$$Sg$$^{b}$$ were produced in the $$^{248}$$Cm($$^{22}$$Ne,5$$n$$) reaction. Decay properties of $$^{265}$$Sg$$^{a,b}$$ were investigated with a rotating-wheel apparatus for $$alpha$$ and spontaneous fission (SF) spectrometry under low background condition attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated $$alpha$$-$$alpha$$ (-$$alpha$$) and $$alpha$$-SF decay chains, 18 and 24 events were assigned to $$^{265}$$Sg$$^{a}$$ and $$^{265}$$Sg$$^{b}$$, respectively. The half-life and $$alpha$$-particle energy of $$^{265}$$Sg$$^{a}$$ were measured to be $$8.5^{+2.6}_{-1.6}$$ s and $$8.84 pm 0.05$$ MeV, respectively, and those of $$^{265}$$Sg$$^{b}$$ were $$14.4^{+3.7}_{-2.5}$$ s and $$8.69 pm 0.05$$ MeV.

Journal Articles

High-temperature continuous operation of the HTTR

Takamatsu, Kuniyoshi; Sawa, Kazuhiro; Kunitomi, Kazuhiko; Hino, Ryutaro; Ogawa, Masuro; Komori, Yoshihiro; Nakazawa, Toshio*; Iyoku, Tatsuo; Fujimoto, Nozomu; Nishihara, Tetsuo; et al.

Nihon Genshiryoku Gakkai Wabun Rombunshi, 10(4), p.290 - 300, 2011/12

A high temperature (950$$^{circ}$$C) continuous operation has been performed for 50 days on the HTTR from January to March in 2010, and the potential to supply stable heat of high temperature for hydrogen production for a long time was demonstrated for the first time in the world. This successful operation could establish technological basis of HTGRs and show potential of nuclear energy as heat source for innovative thermo-chemical-based hydrogen production, emitting greenhouse gases on a "low-carbon path" for the first time in the world.

Journal Articles

Decay properties of $$^{266}$$Bh and $$^{262}$$Db produced in the $$^{248}$$Cm + $$^{23}$$Na reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06

 Times Cited Count:30 Percentile:77.75(Physics, Multidisciplinary)

Decay properties of an isotope $$^{266}$$Bh and its daughter nucleus $$^{262}$$Db produced by the $$^{248}$$Cm($$^{23}$$Na,5$$n$$) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. $$^{266}$$Bh was clearly identified from the correlation of the known nuclide, $$^{262}$$Db. The obtained decay properties of $$^{266}$$Bh and $$^{262}$$Db are consistent with those observed in the $$^{278}$$113 chain, which provided further confirmation of the discovery of $$^{278}$$113.

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